/*
 * Copyright 2017 - 2025 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see [https://www.gnu.org/licenses/]
 */

package infra.lang;

import java.io.Serial;
import java.io.Serializable;

/**
 * Simple serializable class that serves as a {@code null} replacement
 * for cache stores which otherwise do not support {@code null} values.
 *
 * @author <a href="https://github.com/TAKETODAY">Harry Yang</a>
 * @since 4.0 2021/9/25 10:42
 */
public final class NullValue implements Serializable {

  @Serial
  private static final long serialVersionUID = 1L;

  public static final NullValue INSTANCE = new NullValue();

  private NullValue() {

  }

  @Serial
  private Object readResolve() {
    return INSTANCE;
  }

  @Override
  public int hashCode() {
    return NullValue.class.hashCode();
  }

  @Override
  public boolean equals(Object obj) {
    return obj == INSTANCE;
  }

  @Override
  public String toString() {
    return "NullValue";
  }

}
